The present invention relates to devices for polishing floors and, in particular, to relatively high-speed burnishing or polishing devices wherein a buffing pad is rotated by a drive pad.
Over the last several decades, floor polishing machines have improved significantly from machines which rotated between one to two hundred revolutions per minute to conventional machines which have high quality buffing pads and which are capable of rotating at relatively high speeds, for example 2200 revolutions per minute or more, when not under a workload. While conventional machines are a significant improvement over the machines of several decades ago, there are still associated problems.
In particular, unless powered by relatively very large engines (often noisy propane engines), conventional machines powered by smaller and quieter engines normally incur significant drag on the buffing pad during use which reduces the rotational rate of the pad to rotational speeds on the order of 1500 to 1600 rpm with a consequent significant reduction in buffing or polishing quality. Buffing at the lower rates of revolution also requires more passes of the pad over a particular area and, consequently, more operator time than if the pad can be rotated at a higher speed.
Applicant has determined through extensive testing that a significant portion of the shine or gloss applied to a floor during buffing by machines of this type is produced by the circumferential portion of the buffing pad closest to the outer edge of the drive pad. Further, applicant has determined that, if the entire weight of the machine is placed on the buffing pad above this outer portion rather than across the entire buffing pad, substantially less drag is placed on the machine as compared to a similarly powered machine having a buffing pad which supports the weight of the buffing machine across the entire or at least a majority of the surface of the buffing pad.
It is noted that modern buffing pads are designed to operate at relatively high rotational speeds. Consequently, applicant undertook to produce a floor polishing apparatus which would be relatively high-speed, yet which would be designed so that the weight of the buffing machine would be substantially all directed to near the outer edge of the buffing pad in order to both reduce the drag and consequently increase the rotational speed of the pad under load for a particular horsepower motor and to provide additional weight to react against the pad at the location where the pad was performing the greatest amount of polishing.
One further problem associated with the high speed conventional polishing machines is that, if the buffing pad strikes a small object at such high rotational speeds, a significant amount of momentum may be imparted to the object and the object can become a very dangerous projectile. For example, the buffing pad may hit a loose screw, nail or the like that has been accidentally left on the floor and possibly hidden by an overlaying counter or the like. This thrown object may then hit the user of the machine or some bystander with sufficient force to cause injury. These pads also rotate at sufficient speed to cause damage to walls or other objects which they strike. And when the polishing pads strike objects, such objects often catch the pad, partly tearing same and thereby leading to greater wear and early replacement of the pad. Further, the pads tend to distribute a substantial amount of dust into the air around the polisher.
Therefore, applicant determined a protective structure was needed to prevent the pad from engaging loose objects laying on the floor and from coming into contact with walls and the like.
In providing a protective structure, it is also necessary to ensure that the protective structure is adjustable so that an operator may adjust the structure as the buffing pad wears or in accordance with the degree to which the floor is flat or bumpy with the latter requiring a slightly higher setting than the former.